Ferromagnetic Resonance in selected nanostructural materials designed for technological applications

摘要

During the past ten years nanostructures have been subject of activeresearch. Fabrication of such systems follows well developed methods. Theincrease in the number of materials available for research and applicationsrequires that the methods of their characterization be even more precise thenbefore. Thin film structures have many advantages for technologicalapplications because of compatibility with integrated circuit design. Themagnetoimpedance, MI (change of impedance of a ferromagnet on application of afield) in 3-layered structures consisting of two magnetic layers separated by anon-magnetic conductive layer has been predicted to show high MI. In many casesthe experimental values of MI effect are smaller than the theoreticalpredictions. Therefore, more careful characterization of the samples is a must.Accordingly, the first part of the present research deals with a ferromagneticresonance, FMR, study of thin films and multilayers containing Fe20Ni80 layerednanocomponents. The second system proposed for ferromagnetic resonance studyconsists of Co/GdCo multilayers prepared by rf-sputtering. It was chosen as amodel system both for convenience and in view of possible applications. Thethird group of magnetic materials for FMR characterization consists of powders:commercial polystyrene beads (Dynabeads-480) and CoNi powders with nanoscaleparticle dimensions. These particles have many biomedical applications. FMR andmicrowave absorption in micron size powders have been studied previously. Morerecently new methods of small particle fabrication have been developed.Therefore their characterization by microwave methods is highly desirable.